* Freescale Quad Serial Peripheral Interface(QuadSPI)

Required properties:
  - compatible : Should be "fsl,vf610-qspi", "fsl,imx6sx-qspi",
		 "fsl,imx7d-qspi", "fsl,imx6ul-qspi",
		 "fsl,ls1021a-qspi"
		 or
		 "fsl,ls2080a-qspi" followed by "fsl,ls1021a-qspi",
		 "fsl,ls1043a-qspi" followed by "fsl,ls1021a-qspi"
  - reg : the first contains the register location and length,
          the second contains the memory mapping address and length
  - reg-names: Should contain the reg names "QuadSPI" and "QuadSPI-memory"
  - interrupts : Should contain the interrupt for the device
  - clocks : The clocks needed by the QuadSPI controller
  - clock-names : Should contain the name of the clocks: "qspi_en" and "qspi".

Required SPI slave node properties:
  - reg: There are two buses (A and B) with two chip selects each.
	 This encodes to which bus and CS the flash is connected:
		<0>: Bus A, CS 0
		<1>: Bus A, CS 1
		<2>: Bus B, CS 0
		<3>: Bus B, CS 1

Example:

qspi0: quadspi@40044000 {
	compatible = "fsl,vf610-qspi";
	reg = <0x40044000 0x1000>, <0x20000000 0x10000000>;
	reg-names = "QuadSPI", "QuadSPI-memory";
	interrupts = <0 24 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&clks VF610_CLK_QSPI0_EN>,
		<&clks VF610_CLK_QSPI0>;
	clock-names = "qspi_en", "qspi";

	flash0: s25fl128s@0 {
		....
	};
};

Example showing the usage of two SPI NOR devices on bus A:

&qspi2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_qspi2>;
	status = "okay";

	flash0: n25q256a@0 {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "micron,n25q256a", "jedec,spi-nor";
		spi-max-frequency = <29000000>;
		reg = <0>;
	};

	flash1: n25q256a@1 {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "micron,n25q256a", "jedec,spi-nor";
		spi-max-frequency = <29000000>;
		reg = <1>;
	};
};